Microbe growth retardation in shingle roofs



Nov. 18, 1969 s. L... RAPAPORT 3,4795130 MIGROBE GROWTH RETARDATION INSHINGLE ROOFS Filed Nov. 17. 1967 FIG] United States Patent 3,479,130MICROBE GROWTH RETARDATION IN SHINGLE ROOF S Stanley L. Rapaport, 260Highway 17-92, Casselberry, Fla. 32707 Continuation-impart ofapplication Ser. No. 398,624,

Sept. 23, 1964, now abandoned. This application Nov. 17, 1967, Ser. No.689,219

Int. Cl. A611 3/00; B27k 3/16, 3/22 US. Cl. 21-61 8 Claims ABSTRACT OFTHE DISCLOSURE A bimetallic strip for attachment to shingle roofs toprevent discoloration by biological action. The two metals employed inthe strip are selected to form an electrical couple to increase ionicrelease. At least one of the metals is selected on the basis of thebiocidal effect of its ionic solutions.

Background of the invention This is a continuation-in-part of mycopending application Serial No. 398,624, filed September 23, 1964, andnow abandoned for Microbe Growth Retardation In Asphalt Shingle Roofs.

In many tropical and semi-tropical areas it is quite common for roofs tobe subject to a dark discoloration with age. While the exact cause ofthis phenomenon is not known, it is believed to be the result ofbiological ac tion, such as microbial or fungal growths. Thediscoloration may be due to the growth itself or may be producedindirectly as a result of the organisms metabolic products. When theproper conditions exist, the discoloration can be so extreme as tochange a white roof to black in a period of a few years. Northerlyexposed roofs change more rapidly than southerly exposed roofs and thecolor change appears to be more pronounced in some neighborhoods than inothers. The change affects roofs of all colors and, in all knowninstances, the color changes are toward black. The blackening is notonly unsightly but also has adverse economic effects in that isincreases the heat absorption of the roof and thus defeats the verypurpose of the light roof in hot climates.

It has been observed that when lead, copper, or zinc is exposed on theroof, as pipe or flashing for example, the water run-off pattern is freeof darkening This is probably due to the growth-retarding effect of theions of slightly soluble salts of these elements. It has been suggestedthat thin metallic strips, such as copper, be mounted on shingled roofsto prevent such darkening. However, it is believed that an improvementin the efficiency of such strips may be achieved by a synergistic effectresulting from the use of two separate metals in such a strip.Accordingly, it is a primary object of the present invention to providea metallic biocidal strip in which the biocidal effect is enhanced to agreater degree than is possible by the use of any single metallicelement.

Another object is to provide a novel method for the manufacture of sucha strip.

Summary of the invention The present invention comprises a bimetallicstrip for application at spaced intervals along a roof. The strip isformed of two metals which form an electrocouple, at least one of themetals being of a type to release ions having a biocidal effect. Afterapplication of such strips to a roof, normal weathering will result inthe production of ions which will be spread over the surface of the roofby the action of rain or dew.

Brief description of the drawing For a further understanding of thepresent invention, attention is directed to the following description,the appended claims and the figures of the attached drawing, wherein:

FIG. 1 illustrates an asphalt shingle roof protected by bimetallicstrips in accordance with the present invention;

FIG. 2 is an enlarged view of a portion of the roof of FIG. 1;

FIG. 3 is an enlarged end view of the roof of FIG. 1;

FIG. 4 is a detail of a metallic strip in accordance with thisinvention;

FIG. 5 is an enlarged view of the surface of the bimetallic strip ofFIG. 4; and

FIG. 6 is an end view of the bimetallic strip of FIG. 5.

Description of the preferred embodiment The ions of a number of metallicelements have been found to have microbiocidal characteristics. Theseelements include, for example, copper, lead, and zinc. The objects ofthe present invention are achieved by applying to a roof surfacebimetallic strips incorporating at least one such metal. If one of themetals of the bimetallic strip is electronegative with respect to theother, galvanic action will take place, accelerating corrosion of theanodic metal when exposed to moisture. This synergistically increasesthe effectiveness of the active metal by substantially increasing itsion release rate. Suitable combinations of metals for such bimetallicstrips would include, for example, copper-lead, and zinc-iron.

With particular reference to FIGS. 13, there is illustrated a roofcomprising shingles 1, which are attached to the roof in the usualfashion. Secured to the roof at spaced intervals along the shingle edgesare bimetallic strips 2. Such strips may be, for example, approximatelyone inch in width and may be secured to the roof by common wire-staples5 spaced at twelve to eighteen inch intervals in such a manner that aportion 3 of each strip is positioned beneath the edge of a row ofshingles While an exposed portion 4 may be contacted by precipitation.Although considerable variation in size and spacing of the bimetallicstrips of this invention may exist depending upon atmosphericconditions, roof slope, etc., it is anticipated that such strips wouldbe provided for at least every fourth row of shingles to a maximumspacing of possibly ten rows of shingles.

It should also be noted that the illustrated strip has a serrated edge.The purpose of such edge is to increase the metal exposure and, thus,the effectiveness of the strip.

It will be understood that various methods of manufacturing a striphaving two exposed metals are available. However, a highly effectivemethod in accordance with the present invention will result in a stripas shown in FIGS. 5 and 6 wherein a copper substrate 8 has depositedthereon solidified globules 7 of lead in a more or less random anddispersed pattern. This effect is achieved by first forming a copperstrip and depositing thereon, by any suitable means, such aselectrodeposition, a layer of lead. The composite strip is then heatedto a temperature in excess of the melting point of the lead but belowthat of the copper. As the lead liquefies, it tends to cohere and formdiscrete globules. Upon cooling, these globules remain as illustrated inFIGS. 5 and 6 forming a highly effective bimetallic strip wherein bothmetallic elements are exposed to'weathering. A similar techniquemay beemployed in the formation of strips of other metallic elements.

It is to be understood that the present invention is not limited to thespecific elements set forth but includes bimetallic roofing strips ofany metals capable of forming electrocouples and releasing ions whichare microbiocidal to the particular micro-organisms involved. Var= iousother modifications of this invention will be apparent to those skilledin the art. Accordingly, the foregoing description is to be construed asillustrative rather than limiting. This invention is limited only by thescope of the following claims.

What is claimed is:

1. A microbiocidal roof structure comprising a plurality of exposed,spaced, longitudinally extending bimetallic strips, each of said stripsincluding two exposed elemental metals capable of forming anelectrocouple, at least one of said metals being selected from the groupconsisting of copper, lead, and zinc.

'2. The structure of claim 1 wherein said metals are copper and lead.

3. The structure of claim 1 wherein said metals are zinc and iron.

4. A microbiocidal strip comprising two exposed elemental metals capableof forming an electrocouple, at least one of said metals being selectedfrom the group consisting of copper, lead, and Zinc.

5. The strip of claim 4 wherein said strip is serrated along at leastone edge to increase metal exposure.

References Cited UNITED STATES PATENTS 2,129,659 9/1938 Easling 117l582,927,052 3/1960 Moudry 204l57.1 3,197,313 7/1965 Greiner l0615 MORRISO. WO-LK, Primary Examiner BARRY S. RICHMAN, Assistant Examiner US. Cl.X.R.

